1. Field of the Invention
The invention is directed to an electrode arrangement for corona discharges, preferably for use in apparatus for the purification of air and other gases and/or for air conditioning.
2. Description of Related Art
Electrostatic filters have been known for several decades for purification of industrial commercial and waste gases. The main users of such electrostatic filters are, above all, power stations and refuse incinerators, the cement industry, iron- and steel works, the chemical industry and the non-ferrous metallurgy, as well as the cellulose industry.
In the course of time, accurate knowledge of industrial production processes has made possible the systematic investigation of all parameters affecting the operation of electrostatic filters.
Dust particles suspended in gas are electrically charged by the electrostatic filter and are conveyed, under the influence of a strong electrical field, to precipitation electrodes where they are deposited. The precipitation electrodes are grounded in common with the filter housing, while corona electrodes (thin wires or bands provided with five points) have a negative polarity and are supported by insulators.
A DC voltage exists between the electrodes which, depending upon filter construction and use, amounts to 20 kV up to over 100 kV. In the direct environment of the corona electrodes, corona discharges occur because of the high field strength. In the course of this, electrons are liberated and the correspondingly negatively charged gas ions which are generated are deposited on the dust particles. These charged particles migrate to the precipitation electrode under the influence of the electrical field, where they give off the charge ("purification of industrial commercial- and waste gases", Lurgi Environmental and Chemical Technology GMbH, Frankfurt am Main).
Although electrostatic filters have been known for more than six decades for purification of industrial commercial and waste gases, the utilization of corona discharges in apparatus for purification of air and other gases and/or for air conditioning is still relatively new.
An electrostatic filter for purifying breathing air in closed spaces of suspended material of all sorts, such as organic and inorganic dust, smoke particles and molecules of chemical compounds, has become known in other arrangements, this filter being equipped with a passive plate precipitator, a corona electrode, a blower and a mechanical coarse filter. In a filter of this type, two interconnected L-shaped section parts from dielectric workpiece are provided, whose legs are rigidly connected in pairs at their free edges by welding, bonding or riveting or such like, the L-shaped section parts being both assembled to form a frame constituting a box open at two diametrically opposite sides, which is enclosable into the apparatus housing, similar to a drawer. The frame is equipped with slots, recesses, bores, etc., in order to increase the electrical leakage paths. The filter plates, which are of different length and charged positively and negatively supported by the frames and their detachable attachment, are provided by continuously stamped retaining springs which hold themselves in grooves, wherein removal of bare ionization frames is provided which carry the ionization wires and the retaining springs stressing the same (DE-OS No. 2 341 626).
The construction of such an electrostatic filter is very expensive, since a plurality of aggregates and arrangements, which can be plugged together, has to be housed in the plastic housing. The air to be purified is conveyed through the filter by means of a blower.